User guide

6-32
VPD and EVCD File Generation
VPD On/Off PLI Rules
Follow these basic rules while using VPD On/Off PLI system tasks:
• You can insert the $vcdpluson and $vcdplusoff tasks in
source code or enter it at the DVE interactive prompt.
• The $vcdpluson and $vcdplusoff tasks accept one level but
multiple scopes/signals as arguments.
• The $vcdpluson and $vcdplusoff tasks, when applied to the
same signals, toggle the recording on and off. The count for each
signal is accumulative; (+,-). ..on/..on/..off leaves the signal
recording on. For example using the hierarchy of Figure 6-7, the
following command sequence will still report on Module D since
it is added twice but only removed once.
$vcdpluson(A); $vcdpluson(B); $vcdplusoff(D);
• On large designs, you should selectively turn signal data capture
(dumping) on or off. Multiple use of $vcdpluson and
$vcdplusoff allow on and off selection.
• The $vcdpluson and $vcdplusoff tasks executed in the same
simulation time period may execute in any order. To ensure that
one or the other executes last, separate them by at least one
simulation time unit.
• Signals that are turned off may have signal value changes
recorded if a higher/ lower level of the same signal is turned on.